** Rexam enters its fourth straight day of gains,rising as much as 11.6 pct in heavy volumes
** Stock up 17.7 pct since hitting two-year lows on Jan. 30.Chart: http://link.reuters.com/zuj93w
** Most-traded on Stoxx 600 by average volumes,with nearly twice the 30-day average traded in the first hour
** Co said on Tuesday it would return around £450mln toshareholders after selling its healthcare arm
** Two traders cite reports bid speculation for co ascatalyst for Thursday's rise, US private equity mentioned
** Earlier this week the FT reported that Rexam is to returnaround £450m to shareholders after co agreed to sell the bulk ofits healthcare business to private equity
(RM: alasdair.pal.thomsonreuters.com@reuters.net)